<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        /*
        #i1{
            background-color: #2459a2;
            height: 48px;
        }
        #i2{
            background-color: #2459a2;
            height: 48px;
        }
        #i3{
            background-color: #2459a2;
            height: 48px;
        }
        .c1{
            background-color: #2459a2;
            height: 10px;
        }
        */
        /*#c2{*/
            /*background-color: black;*/
            /*color: white;*/
        /*}*/

        /*.c1 div{*/
            /*background-color: black;*/
            /*color: white;*/
        /*}*/
        .i1,.i2,.i3{
             background-color: black;
            color: white;
        }
        .c1[n='alex']{ width:100px; height:200px; }
    </style>
</head>
<body>
    <div class="i1">ff</div>
    <div class="i2">ff</div>
    <div class="i3">2</div>
    <input class="c1" type="text" n="alex">
    <input class="c1" type="password">
</body>
</html>